Hybrid die cast system for forming a component usable in a gas turbine engine

ABSTRACT

A hybrid die cast system ( 10 ) having an inner liner insert ( 12 ) that enables the configuration of a component ( 18 ) produced by the system ( 10 ) to be easily changed by changing the inner liner insert ( 12 ) without having to rework the die housing ( 16 ) is disclosed. Because the inner liner insert ( 12 ) only need be removed and replaced to change the configuration of an outer surface ( 18 ) of a component ( 18 ) produced by the system ( 10 ), the cost savings is significant in contrast with conventional systems in which the die would have to be reworked. The system ( 10 ) may also include a cooling system ( 20 ) for controlling the casting process by controlling the rate of solidification and the rate of cooling of the casting. Local heating and cooling may be used to control the microstructure, enhance mold fill and reduce casting defects such as porosity.

FIELD OF THE INVENTION

This invention is directed generally to die cast systems, and moreparticularly to manufacturing methods for turbine airfoils usable inturbine engines.

BACKGROUND

Die casting is traditionally limited to the casting of non-ferrousalloys because it is challenging to use the die cast process for hightemperature materials such as nickel based superalloys. In the die castprocess, molten metal may be forced into a mold under high pressure.This process is typically used for large volume production as there is ahigh initial capital investment cost associated with manufacturing thedies. Most die castings are made from non-ferrous alloys such as zinc,aluminum, and magnesium. Die casting is capable of producingdimensionally consistent parts.

Investment casting using a lost wax process is typically employed formanufacturing turbine components made from high temperature materials,such as nickel based superalloys. Investment casting is often used toform components, such as blades, vanes and ring segments. Investmentcasting is a versatile process that enables the casting of complexshapes that are not possible with traditional die casting. Internalcavities may be incorporated into a turbine component through use of thecores with the investment casting process.

SUMMARY OF THE INVENTION

A hybrid die cast system having an inner liner insert that enables theconfiguration of a component produced by the system to be easily changedby changing the inner liner insert without having to rework a diehousing is disclosed. Because the inner liner insert only need beremoved and replaced to change the configuration of an outer surface ofa component produced by the system, the cost savings is significant incontrast with conventional systems in which the die would have to bereworked. The system may also include a die cooling system forcontrolling the casting process by controlling the rate ofsolidification and the rate of cooling of the casting. Local heating andcooling may be used to control the microstructure, enhance mold fill andreduce casting defects such as porosity.

In at least one embodiment, the hybrid die cast system may include a diehousing having one or more inner chambers and one or more inner linerspositioned within the inner chamber of the die housing. The inner linermay have an inner surface defining boundaries useful to form an outersurface of a component. In at least one embodiment, the inner surface ofthe inner liner may be configured to form the component of a gas turbineengine. In another embodiment, the inner surface of the inner liner maybe configured to form an airfoil usable in a gas turbine engine. Thehybrid die cast system may include one or more casting cores positionedin the inner chamber of the die housing to create an inner coolingsystem within the airfoil. The hybrid die cast system may also includeone or more intermediate liners positioned between the inner liner andan inner surface of the inner chamber in the die housing. Theintermediate liner may be formed from one or more compliant materialsallowing for differential expansion to occur.

The hybrid die cast system may also include one or more die coolingsystems formed from one or more serpentine cooling channels positionedwithin the inner liner. The die cooling system may include one or morecooling fluid supply manifolds in fluid communication with inlets of aplurality of cooling channels and one or more cooling fluid collectionmanifolds in fluid communication with outlets of the plurality ofcooling channels. The die cooling system may also include one or morevalves for controlling flow of cooling fluids through the die coolingsystem. The hybrid die cast system may also include one or more dieheating systems formed from one or more heating channels positionedwithin the die housing.

A method of forming a component of a gas turbine engine is disclosed.The method may include positioning one or more casting cores in an innerchamber of a die housing, wherein the die housing has at least one innerchamber and at least one inner liner positioned within the inner chamberof the die housing and wherein the inner liner may have an inner surfacedefining boundaries useful to form an outer surface of a component. Themethod may also include injecting molten metal into the inner chamber ofthe die housing defined by the inner surface of the inner liner. Themethod may also include controlling a rate of solidification and a rateof cooling of the casting via at least one die cooling system formedfrom one or more serpentine cooling channels positioned within the innerliner and including one or more cooling fluid supply manifolds in fluidcommunication with inlets of a plurality of cooling channels, one ormore cooling fluid collection manifolds in fluid communication withoutlets of the plurality of cooling channels and one or more valves forcontrolling flow of cooling fluids through the die cooling system.

An advantage of the hybrid die cast system is that because the innerliner insert only need be removed and replaced to change theconfiguration of an outer surface of a component produced by the system,a significant cost savings is captured in contrast with conventionalsystems in which the die would have to be reworked.

Another advantage of the hybrid die cast system is that the die coolingsystem and die heating system may be used to control the rate ofsolidification and the rate of cooling of the casting component andlocal heating and cooling may be used to control the microstructure,enhance mold fill and reduce casting defects such as porosity.

Yet another advantage of the hybrid die cast system is that the diecooling system and die heating system may be used to retain molten alloyin certain locations of the casting component, especially in sectionswhere mold fill may otherwise be difficult.

Another advantage of the hybrid die cast system is that use of thehybrid die cast system will reduce time and effort required to build ashell in a conventional casting process.

These and other embodiments are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate embodiments of the presently disclosedinvention and, together with the description, disclose the principles ofthe invention.

FIG. 1 is a cross-sectional view of the hybrid die cast system.

FIG. 2 is a cross-sectional view of the die cooling system and heatingsystem of the hybrid die cast system.

FIG. 3 is cross-sectional view of another embodiment of the die coolingsystem and heating system of the hybrid die cast system.

FIG. 4 is a perspective view of an airfoil usable in a gas turbineengine.

FIG. 5 is a cross-sectional view of the airfoil shown in FIG. 5 taken atsection line 5-5 in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1-5, a hybrid die cast system 10 having an inner linerinsert 12 that enables the configuration of a component 14 produced bythe system 10 to be easily changed by changing the inner liner insert 12without having to rework a die housing 16 is disclosed. Because theinner liner insert 12 only need be removed and replaced to change theconfiguration of an outer surface 18 of a component 14 produced by thesystem 10, the cost savings is significant in contrast with conventionalsystems in which the die would have to be reworked. The system 10 mayalso include a die cooling system 20 for controlling the casting processby controlling the rate of solidification and the rate of cooling of thecasting. Local heating and cooling may be used to control themicrostructure, enhance mold fill and reduce casting defects such asporosity.

In at least one embodiment, the hybrid die cast system 10 may include adie housing 16 having at least one inner chamber 22 and one or moreinner liners 12 positioned within the inner chamber 22 in the diehousing 16. The inner liner 12 may have an inner surface 24 definingboundaries useful to form an outer surface 18 of a component 14. One ormore inner liners 12 may be positioned within the inner chamber 22 ofthe die housing 16 such that the inner liner 12 may have an innersurface 24 defining boundaries useful to form an outer surface 18 of acomponent 14. In at least one embodiment, the inner surface 24 of theinner liner 12 may be configured to form the component 14 of a gasturbine engine, as shown in FIGS. 4 and 5. In yet another embodiment,the inner surface 24 of the inner liner 12 may be configured to form anairfoil 28 usable in a gas turbine engine. The airfoil 28 may be formedfrom a generally elongated, hollow airfoil 60 having a leading edge 62on an opposite side from a trailing edge 64 and separated by a concavepressure side 66 and a convex suction side 68. One or more casting cores61 may be positioned in the inner chamber 22 of the die housing 16 toform one or more channels of an internal cooling system in the airfoil28. In at least one embodiment, as shown in FIG. 1, the die housing 16may be formed from a first die subhousing 56 and a second die subhousing58.

In at least one embodiment, the inner liner 12 may be formed, at leastin part, from one or more ceramic materials. The ceramic liner 12 mayform a shell that may be used to produce features in the casting thatwould not be possible with conventional die casting due to pull-planerestrictions. The ceramic liner 12 may be formed in any appropriatemanner, such as, but not limited to, flexible silicon technology, or anadditive manufacturing process, such as, but not limited to, threedimensional printing or selective laser melting. The configuration ofthe inner surface 24 of the ceramic liner 12 may be changed to changethe configuration of the outer surface 18 of a component 14 formedwithin the hybrid die cast system 10 without having to rework the diehousing 16. As such, a significant cost savings is realized. Inaddition, the ceramic liner 12 may also provide a barrier between themolten metal used to form the component 14 within the inner chamber 22of the liner 12, thereby preventing the molten metal from contacting thedie housing 16 during the casting process.

In at least one embodiment, the hybrid die cast system 10 may includeone or more intermediate liners 30 positioned between the inner liner 12and an inner surface 32 of the inner chamber 22 in the die housing 16.The intermediate liner 30 may be formed from one or more compliantmaterials allowing for differential expansion to occur. The intermediateliner 30 may accommodate any dimensional mismatch between the diehousing 16 and the inner liner 12. In at least one embodiment, theintermediate layer 30 may be formed from an unfired ceramic, i.e. greenstate.

The hybrid die cast system 10 may also include one or more die coolingsystems 20 formed from one or more cooling channels 38 or one or moreheating systems 36, or both, for controlling the casting process. Theheating and cooling systems 20, 36 may be used to control the rate ofsolidification and the rate of cooling of the casting component 14.Local heating and cooling may be used to control the microstructure,enhance mold fill and reduce casting defects such as porosity. Theheating and cooling systems 20, 36 may be used to retain molten alloy incertain locations of the casting component 14, especially in sectionswhere mold fill may otherwise be difficult. The cooling system 20 may beconfigured to provide cooling to the hybrid die cast system 10 viaembedded cooling channels 38. The cooling fluid used within the coolingsystem 20 may be, but is not limited to being, a gas, e.g. air or otherinert gas, or a liquid, e.g. water, oil, polymer solution, molten salt,or liquid metal such as aluminum or tin. The heating and cooling systems20, 36 may be used to form temperature gradients within the hybrid diecast system 10 to promote directional solidification.

In at least one embodiment, the die cooling system 20 may be formed fromone or more serpentine cooling channels 38 positioned within the innerliner 12. The one cooling channels 28 may be positioned at an interface40 between the liner 12 and one or more intermediate liners 30,positioned between the liner 12 and the inner surface 32 defining theinner chamber 22 in the die housing 16, positioned within the innerliner 12, positioned within the die housing 16, positioned within theintermediate liner 30, or any combination thereof. In anotherembodiment, the die cooling system 20 may include one or more coolingfluid supply manifolds 42 in fluid communication with inlets 44 of aplurality of cooling channels 38 and one or more cooling fluidcollection manifolds 46 in fluid communication with outlets 48 of theplurality of cooling channels 38. One or more cooling circuits may beformed within the die cooling system 20. In at least one embodiment,multiple cooling circuits may be formed within the die cooling system20. The die cooling system 20 may also include one or more valves 50 forcontrolling flow of cooling fluids through the die cooling system 20,and in particular, through the plurality of cooling circuits. In atleast one embodiment, the die cooling system 20 may include a pluralityof valves configured to control the cooling system 20 to switch thecooling fluid on and off in a manner that allows the cooling fluid tomove according to the solidification location of the liquid metal. Thedie cooling system 20 may also include one or more chill plates 54. Inat least one embodiment, the chill plate 54 may be positioned within thedie housing 16.

The hybrid die cast system 10 may also include one or more die heatingsystems 36 formed from one or more heating channels 52 positioned withinthe die housing 16. The heating system 36 may include electricalresistance heating elements 54, which, in at least one embodiment, maybe strategically placed induction coils 54 or other appropriate heatsources. One or more aspects of the heating system 36, such as, but notlimited to the heating channels 52, may be positioned at an interface 40between the liner 12 and one or more intermediate liners 30, positionedbetween the liner 12 and the inner surface 32 defining the inner chamber22 in the die housing 16, positioned within the inner liner 12,positioned within the die housing 16, positioned within the intermediateliner 30, or any combination thereof. As shown in FIG. 3, the hybrid diecast system 10 may include the die cooling system 20 and the heatingsystem 36 to move a thermal field, and more specifically, to achievecrystal growth through use of a plurality of circuits with the diecooling system 20 in conjunction with the heating system 36.

The hybrid die cast system 10 may be used in a number of manners. In atleast one embodiment, the hybrid die cast system 10 may be used in amethod of forming a component 14 of a gas turbine engine includingpositioning one or more casting cores 61 in at least one inner chamber22 of a die housing 16, whereby the die housing 16 may have one or moreinner chambers 22 and one or more inner liners 12 positioned within theinner chamber 22 of the die housing 16. The inner liner 12 may have aninner surface 24 defining boundaries useful to form an outer surface 26of a component 14. The method may also include injecting molten metalinto the inner chamber 22 of the die housing 16 defined by the innersurface 24 of the inner liner 12. The method may also includecontrolling a rate of solidification and a rate of cooling of thecasting via one or more die cooling systems 20 formed from at least oneserpentine cooling channel 38 positioned within the inner liner 12 andone or more cooling fluid supply manifolds 42 in fluid communicationwith inlets 44 of a plurality of cooling channels 38, at least onecooling fluid collection manifold 46 in fluid communication with outlets48 of the plurality of cooling channels 38 and at least one valve 50 forcontrolling flow of cooling fluids through the die cooling system 20.

The foregoing is provided for purposes of illustrating, explaining, anddescribing embodiments of this invention. Modifications and adaptationsto these embodiments will be apparent to those skilled in the art andmay be made without departing from the scope or spirit of thisinvention.

We claim:
 1. A hybrid die cast system (10), characterized in that: a diehousing (16) having at least one inner chamber (22); and at least oneinner liner (12) positioned within the at least one inner chamber (22)of the die housing (16), wherein the at least one inner liner (12) hasan inner surface (24) defining boundaries useful to form an outersurface (18) of a component (18).
 2. The hybrid die cast system (10) ofclaim 1, characterized in that the inner surface (24) of the at leastone inner liner (12) may be configured to form the component (18) of agas turbine engine.
 3. The hybrid die cast system (10) of claim 1,characterized in that the inner surface (24) of the at least one innerliner (12) may be configured to form an airfoil (28) usable in a gasturbine engine.
 4. The hybrid die cast system (10) of claim 1, furthercharacterized in that at least one intermediate liner (30) positionedbetween the at least one inner liner (12) and an inner surface (32) ofthe at least one inner chamber (22) in the die housing (16).
 5. Thehybrid die cast system (10) of claim 4, characterized in that theintermediate liner (30) may be formed from at least one compliantmaterial allowing for differential expansion to occur.
 6. The hybrid diecast system (10) of claim 1, further characterized in that at least onecasting core (61) positioned in the at least one inner chamber (22) ofthe die housing (16).
 7. The hybrid die cast system (10) of claim 1,further characterized in that at least one die cooling system (20)formed from at least one cooling channel (38).
 8. The hybrid die castsystem (10) of claim 7, characterized in that the at least one diecooling system (20) is formed from at least one serpentine coolingchannel (38) positioned within the at least one inner liner (12).
 9. Thehybrid die cast system (10) of claim 7, characterized in that the diecooling system (20) further comprises at least one cooling fluid supplymanifold (42) in fluid communication with inlets (44) of a plurality ofcooling channels (38) and at least one cooling fluid collection manifold(46) in fluid communication with outlets (48) of the plurality ofcooling channels (38).
 10. The hybrid die cast system (10) of claim 7,characterized in that the die cooling system (20) further comprises atleast one valve (50) for controlling flow of cooling fluids through thedie cooling system (20).
 11. The hybrid die cast system (10) of claim 1,further characterized in that at least one die heating system (36)formed from at least one heating channel (52) positioned within the diehousing (16).